Concrete Construction Online Magazine: Placing & Finishing

Expansion Joints

Mon, 1 Oct 2012 06:06:08 EST

Are expansion joints necessary?

Bulging Joint Fillers

Fri, 16 Dec 2011 01:38:27 EST

Under resilient floors, what is less likely to telegraph joints after moisture equilibration: semirigid epoxy or polyurea?

Pigment Effects on Concrete Properties

Fri, 16 Dec 2011 01:26:25 EST

Besides changing the color, does adding pigment to concrete have any other effects on its properties that a contractor should be aware of?

Adding Water to Concrete on the Jobsite

Sun, 12 Dec 2010 01:37:34 EST

Under what conditions are we allowed to retemper ready-mixed concrete at the jobsite? If we receive a batch that has too low a slump, can we add water to make the concrete more workable?

Depth of Isolation Joints

Sun, 12 Dec 2010 01:39:28 EST

Do I need to cut completely through a slab to form isolation joints?

Concrete Expansion Joints

Wed, 15 Dec 2010 03:14:24 EST

Are joints in concrete meant to accommodate expansion or contraction? Someone told me that what I've always called expansion joints I should now call contraction joints. Does this mean that concrete doesn't expand? What are these joints actually supposed to do?

Concrete and Copper Concerns

Sun, 12 Dec 2010 08:36:16 EST

We've been asked to place a concrete pad as the floor for a newhome, on a base of crushed limestone. There will be copper water pipescoming up through the floor. Are there any reasons for concern about a chemical reaction between the limestone and the copper pipe?

Preparing for an SCC Pour

Thu, 16 Dec 2010 02:18:16 EST

We have our first large self-consolidating concrete (SCC) project coming up soon, so I want to ensure that we get this right. The engineer performed the required test mixes to confirm slump, flow, spread, and compressive strength performance. The mix from

Fixing a Curling Floor

Sun, 12 Dec 2010 08:40:42 EST

The contractor says it is a workmanship problem between me and the excavator. What are your thoughts on this and how should I go about repairing it? The contractor suggested pumping grout under the floor at the joints, but I don't think that is a good ide

Grinding Questions From a Novice

Tue, 5 Jun 2012 05:06:47 EST

I am the building manager for a large church on the East Coast. We recently have contracted with a company to grind and overlay about 5000 square feet of our church.

Did Salt Finish Affect Color?

Mon, 13 Dec 2010 10:16:36 EST

I am the building manager for a large church on the East Coast. We recently have contracted with a company to grind and overlay about 5000 square feet of our church.

Is Slump Test Outdated?

Mon, 13 Dec 2010 10:16:23 EST

A lot of the concrete we're now placing would be considered “low slump.” Years ago it would have meant trouble for the crew. But today, we're able to work with most of the low slump concrete we get. Is the slump test outdated?

Problem Clinic: How Curling Happens and How to Control It

Sun, 12 Dec 2010 08:48:35 EST

I am about to install a 10,000-square-foot floor and the owner believes that wet curing the floor will result in no curling. Is this true?

Correcting for Aggregate Moisture

Sun, 12 Dec 2010 08:37:40 EST

Q: I'm fairly new in the concrete business and I know that a mix's water-cement ratio affects how well the concrete turns out, but as a contractor why should I care about something called "aggregate moisture?"

Curing

Sun, 12 Dec 2010 08:48:34 EST

Questions about the effects on curing of temperature and superplasticizers.

Early Morning Slab Pours

Fri, 17 Dec 2010 10:44:08 EST

I am a concrete contractor in the Southwest and to beat the heat in the summertime, I cast my slabs early in the morning, starting before dawn. By avoiding the heat of the day, doesn't this reduce the need for curing?

Testing Curing Effectiveness

Fri, 17 Dec 2010 10:46:42 EST

What tests can I use to determine if the curing has been effective?

Does Superplasticizer Reduce Need for Curing Water?

Fri, 17 Dec 2010 10:45:50 EST

I am using a superplasticizer in my concrete. I have heard that since this is a water-reducer, the need for curing water is reduced. Is this correct?

On the Questionable, and Perhaps Lost, Art of Curing Concrete

Sun, 12 Dec 2010 08:46:59 EST

I have a project specification that requires fog spraying, followed by curing compound, followed by wet cure with burlap and soaker hoses. Why the complicated curing requirements? Isn't this a case of specification-overkill?

Concrete expansion joints

Mon, 13 Dec 2010 10:16:18 EST

I was told that what we used to call expansion joints I should now call contraction joints. Does that mean that concrete doesn't expand?